The invention relates to locating a device using a database containing hybrid location data. More particularly, the invention relates to locating a device using a database which correlates location measurements having different accuracies.
It is sometimes desirable to measure and report the location of an object. For example, if a person makes an emergency telephone call using, for example, a cellular telephone, it may be important to know the location of the person in order to render the requested aid. Further, it may be useful to track the locations of a company""s employees while they are at work in order to route telephone calls or other services to them.
A device, such as a cellular telephone or a personal digital assistant (PDA), may be able to determine its location by measuring certain signal parameters, such as signal strength and the angle of arrival of the signal from a source, assuming the location of the source is known. The device may then compute, based on the signal parameters and the angle of arrival, its location and report it to a computer system which can, for example, store it in a database or make other use of the information.
Some devices may be capable of performing such location measurements using two sources. For example, a cellular telephone equipped with a local area wireless interface, such as Bluetooth, may be capable of measuring its location relative to a cellular base station, which has a known location, and its location relative to the local area transmitter, such as a Bluetooth transceiver with a known location. The relative accuracy of the measurements made with respect to the two sources may be such that one of the measurements is more accurate than the other.